This invention relates to branched polymers containing dendritic branches having functional groups uniformly distributed on the periphery of such branches. This invention also relates to processes for preparing such polymers as well as applications therefore
Star branched are known polymers which are characterized as having so-called star structured branching wherein the individual branches radiate out from a nucleus and there are at least 3 branches per nucleus. Such star branched polymers are illustrated by the polyquaternary compositions described in U.S. 4,036,808 and 4,102,827. Star branched polymers prepared from olefins and unsaturated acids are described in U.S. Pat. No. 4,141,847. The star branched polymers offer several advantages over polymers having other types of branching. For example, it is found that the star branched polymers may exhibit higher concentrations of functional groups thus making them more active for their intended purpose. In addition, such star branched polymers are often less sensitive to degradation by shearing which is a very useful property in formulations such as paints, in enhanced oil recovery and other viscosity applications. Additionally, the star branched polymers have relatively low intrinsic viscosities even at high molecular weight.
While the star branched polymers offer many of the aforementioned advantages over polymers having more conventional branching, it has been highly desirable to provide polymers which exhibit even greater concentrations of functional groups per unit volume of the polymer macromolecule as well as a more uniform distribution of such functional groups in the exterior regions of the macromolecule. In addition, it is often desirable to provide polymers having macromolecular configurations that are more spheroidal and compact than are the star branched polymers. These and other advantages have been achieved by the dense star polymers disclosed in U.S. Pat. No. 4,587,329. However, such dense star polymers often do not possess properties which are particularly desirable for ion-exchange resins.
Therefore, it would be very desirable to provide an improved dense star polymer having properties which render them particularly suitable as ion-exchange resins and chelation resins.